“The only thing holding us back is cracking the code on making carbon nanotubes at scale.”

‒ Benji Maruyama, Air Force Research Laboratory.

UC’s Nanoworld Lab directs the collective work of 30 graduate and undergraduate students.

One of them, UC research associate Sathya Narayan Kanakaraj, co-authored a study examining ways to improve the tensile strength of dry-spun carbon nanotube fiber. His results were published in June in the journal Materials Research Success.

Graduate student Mark Haase, spent the past year exploring applications for carbon nanotubes at the Air Force Research Lab of Wright-Patterson. Through the partnership, UC students use the Air Force Lab’s sophisticated equipment, including X-ray computer tomography, to analyze samples. Haase has been using the Air Force equipment to help his classmates with their projects as well.

“This pushes us to work in groups and to specialize. These are the same dynamics we see in corporate research and industry,” Haase said. “Engineering is a group activity these days so we can take advantage of that.”

“We have the luxury in academia to explore different applications. Not all of them may see the market. But even if 10 percent hit, it would be a great success.”

‒ Vesselin Shanov, UC professor of chemical and materials engineering

UC researchers “grow” nanotubes on quarter-sized silicon wafers under heat in a vacuum chamber through a process called chemical vapor deposition.

“Each particle has a nucleation point. Colloquially, we can call it a seed,” Haase said.

“Our carbon-containing gas is introduced into the reactor. When the carbon gas interacts with our ‘seed,’ it breaks down and reforms on the surface. We let it grow until it reaches the size we want,” he said.

Researchers can use almost any carbon, from alcohol to methane.

“I remember one group showed off by using Girl Scout cookies. If it contains carbon, you can turn it into a nanotube,” Haase said.

UC’s Nanoworld Lab set a world record in 2007 by growing a nanotube that stretched nearly 2 centimeters, the longest carbon nanotube array produced in a lab at the time. Today’s labs can create nanotubes that are many times longer.

UC researchers stretch the little fibrous square over an industrial spool in the lab. Suddenly, this tiny sheet of carbon becomes a spun thread that resembles spider’s silk that can be woven into textiles.

“It’s exactly like a textile,” Shanov said. “We can assemble them like a machine thread and use them in applications ranging from sensors to track heavy metals in water or energy storage devices, including super capacitors and batteries.”

For the military, this could mean replacing heavy batteries that charge the growing number of electronics that make up a soldier’s loadout: lights, night-vision and communications gear.

“As much as one-third of the weight they carry is just batteries to power all of their equipment,” Haase said. “So even if we can shave a little off that, it’s a big advantage for them in the field.”

Medical researchers are investigating how carbon nanotubes can help deliver targeted doses of medicine.

“On the outside, you can add a protein molecule. Cells will read that and say, ‘I want to eat that.’ So we can deliver medicine to support healthy cells, to restore sick cells or even to kill cancer cells,” Haase said.

But first researchers want to make sure that carbon nanotubes are nontoxic.

“That’s why they’ve been moving slowly,” Haase said. “Research has found that in high or acute exposure, carbon nanotubes can cause lung damage similar to asbestos. The last thing we want to do is cure one cancer with these only to find it gives you a different one.”

Preliminary results have been promising.

Source: University of Cincinnati